The studies supported by this Grant are designed to examine organizational and functional properties of cerebellar afferent and efferent systems interconnecting the cerebellum and the spinal cord. One series of experiments will investigate the segmental action of the reticulospinal and rubrospinal projections activated by the output of the dentate nucleus. Particular emphasis will be directed toward elucidating the effects of these systems on exteroceptive segmental reflexes. Another series of experiments will examine the changes in the activity of simultaneously recorded Purkinje cells in the anterior lobe of the cerebellum in response to applied exteroceptive and proprioceptive stimuli. These data will be quantitated using auto- and cross correlograms as well as Wiener kernel analysis.